IPCC Expert Meeting on Geoengineering

Annex 5: Breakout Group Reports
Breakout Group II.2: Solar Radiation Management Issues and Risks
Chair: Catherine Redgwell
Rapporteur: Clarisse Kehler-Siebert
The summary that follows, written by the Chair and Rapporteur, characterizes the main points of the BOG II.2 discussion. It
may not reflect the personal views of the BOG’s Chair and Rapporteur. The summary is intended for consideration by <strong>IPCC</strong>
authors of the Fifth Assessment Report (AR5), but is neither endorsed nor approved by the <strong>IPCC</strong> or its Working Groups.
Participants in the BOG considered a series of questions related to geoengineering research, developed by the meeting’s
Scientific Steering Group.
Questions suggested for discussions:
What are the most important issues or dimensions related to Solar Radiation Management that <strong>IPCC</strong> authors might
want to consider in the AR5 (e.g., governance issues, physical science issues, etc.)?
What are the most important aspects of these issues to evaluate (e.g., unintended side effects, risks and uncertainties,
indirect/social costs, legal and governance issues)?
Can the most important aspects of these issues be supported by reference to the peer-reviewed literature, ideally
drawing from multiple lines of independent evidence? What is the available evidence and what are relevant
references?
Introduction
This BOG discussion focused predominantly on Solar Radiation Management (SRM) issues that might be considered in the
<strong>IPCC</strong> AR5 and their means of evaluation—that is, responding to the first two questions above. The final question regarding
sources was addressed only cursorily.
What are the most important issues or dimensions related to Solar Radiation Management (SRM) that <strong>IPCC</strong>
authors might want to consider in the AR5 (e.g., governance issues, physical science issues, etc.)?
The difficulty of assessing regional impact was identified as an issue that might be considered by AR5 authors. BOG
participants proposed that assessing regional impacts of SRM is a governance issue (as opposed to a (purely) physical
science issue). Work published today that does provide insight on regional impacts of global scale SRM is tentative. BOG
participants proposed that while it would not be imprudent to trust extant predictions, there is also significant agreement
that optimal forcing for one region would not be optimal for another region. It was proposed that the regional issues could
be dealt with in various parts of AR5, including within Working Group I, and/or in the Working Group III chapter on
national-international linkage (Chapter 13).
The detection and attribution of cause and effect was also identified by the BOG as a complex issue. From a scientific
standpoint, it is difficult to attribute cause and effect in context of SRM. Thus, AR5 authors might consider the question of
how well are we able to detect and attribute cause and effect for SRM. Furthermore, legal dimensions are also germane
and complex. The question was also raised, but unanswered, as to whether <strong>IPCC</strong> AR5 authors should address liability and
compensation. Finally, it was proposed that AR5 authors might question the increased complexity black carbon causes for
this question of cause and effect.
<strong>IPCC</strong> AR5 authors may wish to consider how SRM is linked to current metrics in climate change. There is no metric to put
these in the same framework—this was considered by some BOG participants as a gap in the literature. Still considering
SRM and climate change, another issue for AR5 authors to consider is the flagging of risk (climate change) v. risk (SRM) to
the ‘external’ world. Furthermore, the question of parallel treatment of issues was discussed: if looking at ethics and SRM,
for example, parallel treatment might be considered for ethics of climate change generally. This led to several questions
about <strong>IPCC</strong> assessment of questions of ethics.
<strong>IPCC</strong> <strong>Expert</strong> <strong>Meeting</strong> on Geoengineering - 83